Rayon fiber, a highly rigid fiber, is used in carcass plies in pneumatic tires, which are a typical rubber article, and in particular in motorcycle tires, in order to achieve high steering stability. Furthermore, lyocell fiber, which is also a cellulose fiber, is more rigid than rayon and thus may be used to obtain even higher steering stability.
For example, JP2006-290164A (PTL 1) discloses a technique for improving steering stability by using rayon as the fiber in the carcass cords of a motorcycle tire.